Answer:
If they are looking for one BEST answer, it is the water.
If looking for top two, it is water and soil.
Realistically, however, this disposal can contaminate all 3.
Let me explain:
The motor oil that is dumped on a driveway first makes its way into the soil. The freshwater found in this soil becomes contaminated with motor oil and can eventually runoff into the ocean. Once this liquid evaporates, it then becomes air pollution. Shortest, best answer tho is water.
Hope this helps. Have a great day!